sliceweasel

1 files changed, 89 insertions, 12 deletions

diff --git a/dot/local/bin/sliceweasel b/dot/local/bin/sliceweasel
index 944f12a..1ec45db 100644
--- a/dot/local/bin/sliceweasel
+++ b/dot/local/bin/sliceweasel
@@ -1,4 +1,5 @@
 #!/bin/bash
+VERBOSE=y
 
 command=iceweasel
 memory_ratio=0.5
@@ -7,20 +8,96 @@ control_group=$command
 as_root=sudo
 
 total_memory() { free -b | (read line; read Mem total _; echo $total); }
-mkdir_idem() { [ -d "$1" ] || $as_root mkdir "$1"; }
 out() { $as_root tee "$@" >/dev/null; }
 
-total_memory=$(total_memory) || exit 1
-memory_limit_in_bytes=$(bc -q <<< "$total_memory * $memory_ratio / 1" )
-control_group_dir=/sys/fs/cgroup/memory/"$control_group"
+die() { printf 'Error: %s\n' "$*" >&2; exit 1; }
+verbose() { [ ! "$VERBOSE" ] || printf '%s\n' "$*" >&2; }
 
-mkdir_idem "$control_group_dir"
-out "$control_group_dir"/memory.limit_in_bytes <<< $memory_limit_in_bytes
+total_memory=$(total_memory) || die "could not ascertain total system memory; probable bug"
+memory_limit_in_bytes=$(bc -q <<< "$total_memory * $memory_ratio / 1" ) || die "process 'bc' failed.  Is it installed?"
 
-# This method works (tested).
-# username=$(id -u)
-# exec sudo -E -- cgexec -g memory:"$control_group" -- su "$username" -c "exec $command"
+init_control_group()
+{
+    control_group_dir=/sys/fs/cgroup/memory/"$control_group"
+    [ -d "$control_group_dir" ] && return
+    $as_root mkdir "$control_group_dir" || die "mkdir failed"
+    set_memory_limit $memory_limit_in_bytes || die "set_memory_limit failed"
+}
 
-# This method is untested.  Should work the same.
-out "$control_group_dir"/cgroup.procs <<< $$
-exec $command
+get_memory_limit()
+{
+    cat "$control_group_dir"/memory.limit_in_bytes
+}
+
+set_memory_limit()
+{
+    prev=$(get_memory_limit)
+    if [ "$1" -ne "$prev" ]; then
+        out "$control_group_dir"/memory.limit_in_bytes <<< $1
+        verbose "changed memory limit ($prev -> $1)"
+    else
+        verbose "memory limit unchanged ($prev)"
+    fi
+}
+
+join_control_group()
+{
+    out "$control_group_dir"/cgroup.procs <<< $$
+}
+
+get_cgroup()
+{
+    local key="$1" pid="${2:-$$}" line val
+    while read line; do
+        line=${line#*:}
+        val=${line#$key:}
+        [ "$val" != "$line" ] || continue
+        echo "$val"
+        return
+    done < /proc/"$pid"/cgroup
+    false
+}
+
+launch_command()
+{
+    init_control_group                      || die "init_control_group failed"
+    cg=$(get_cgroup memory)                 || die "failed to ascertain current control group"
+    [ "$cg" = / ]                           || die "current control group should be '/', but is instead '$cg'"
+    join_control_group                      || die "join_control_group failed"
+    exec $command "$@"
+}
+
+pretty_show_memory_limit()
+{
+    local memory_limit="$(get_memory_limit)"
+    printf "current memory limit: %d bytes (%d%%)\n" \
+           "$memory_limit" \
+           "$((memory_limit * 100 / total_memory))"
+}
+
+resize_control_group()
+{
+    init_control_group
+    case "$1" in
+        '') pretty_show_memory_limit >&2 ;;
+        [0-9]*%) set_memory_limit $((total_memory * "${1%\%}" / 100)) ;;
+        [0-9]*) set_memory_limit "$1" ;;
+        [-+*/][0-9]*) set_memory_limit $(( $(get_memory_limit) "$1" )) ;;
+    esac
+}
+
+usage()
+{
+    cat >&2 <<EOF
+usage: ${0##*/} [--resize|--resize <bytes>|--resize=<bytes>] [--] [pass-through-options] [...]
+       ${0##*/} --help
+EOF
+}
+
+case "$1" in
+    --) shift; launch_command "$@" ;;
+    --resize) resize_control_group "$2" ;;
+    --resize=*) resize_control_group "${1#--resize=}" ;;
+    --*) usage; [ "$1" = '--help' -o "$1" = '--usage' ] ;;
+    *) launch_command "$@" ;;
+esac